i8 INTRODUCTION 



unicoloured. As in the mammalia generally, the under is fre- 

 quently lighter than the upper side, and in some exotic species 

 approaches pure white. The ordinary pelage tints are browns 

 of varying shades, but brilliant yellow, rufous, white, blue-grey, 

 and black sometimes appear in certain foreign species. In a 

 few cases there is a conspicuous " piebald " coloration due to 

 the combination of strongly contrasted shades, as in Scotophilus 

 ornatus (Blyth). An African false vampire {Lavia frons, of 

 Geoffroy) is said to derive the orange colour of its fur from a 

 powder secreted by a gland. 



Bats may follow any local or geographical tendency to 

 develop certain tints which manifests itself amongst other verte- 

 brates, as when in dry arid regions they assume the character- 

 istic " desert " coloration.^ 



Many species, such as the Pipistrelle, are characterised by a 

 wide range of colour variation, amongst which three phases — 

 brown, rufous, and dusky — are conspicuous, but are connected by 

 many intermediate types. The last corresponds to melanism in 

 other mammals, and may be regarded as an almost normal 

 form of variation. Albinism, on the other hand, occurs as an 

 abnormality, probably pathological — which may affect the whole 

 body, including the eyes, wings or ears, or may be restricted to 

 certain definite regions only. 



Sexual differences of coloration are said to exist in the 

 Serotine, but I cannot find them in this or any other 

 British bat. In Dobson's experience females are usually 

 darker than males, but in certain South African instances the 

 reverse is said to be the case.^ The most conspicuous 

 examples occur in India, where the female of Hipposiderus 

 fulvus assumes a vivid coloration during the breeding season. 

 In Scotophilus kuhlii, a common bat at Calcutta, the under- 

 side of the pregnant female changes from pale straw colour or 

 whitish to rich saffron, "exceeding that of the canary bird." * 



The colour distinctions between young and old, and 



1 E.g., Thomas' Rhinolophus denti of Kuruman, South Africa I^Ann. Mag. Nat. 

 Hist, May 1904, 386) ; and his Vespettilio matschiei of Aden {Ann. Mag. Nat. 

 Hist., Nov. 1905, 573. 



2 E.g., Miniopterus dasythrix of Temminck and M. fraterculus of Thomas and 

 Schwann ; see Proc. Zool. Soc. (London), 20th Feb. 1906, 161-162. 



^ Proc. Zool. Soc. (London), 4th March 1873, 241-252. 



